The present invention relates to methods of color-matching paint formulations to target substrates.
Color-matching paint is an important step in the automobile repair process. It is also one of the most variable steps in the repair process. Typically, automobiles are assigned a paint color code by the manufacturer. This paint color code is often used by the paint formulator to generate an initial or starting point paint formulation. Starting point paint formulations can also be identified using spectrophotometric or xe2x80x9cpaint variancexe2x80x9d techniques.
The xe2x80x9cpaint variancexe2x80x9d method of matching paints is based on the measurement of color variability on actual vehicles. Vehicle colors can vary within an assembly plant or from plant to plant due to different paint chemistries. Some paint manufacturers survey vehicles from the different assembly plants and, based on the surveys, measure the variability of the color. Using this information, the paint manufacturer determines the variances in their formulation in order to best match the paint of a specific vehicle. A formulation deck contains the primary formula and variance formulations applied on a card. The formulation decks are typically updated about every six months and distributed to the painters under a fee-based service contract.
Often times, however, the formulation that the painter mixes based on the formulation deck recommendation does not provide an acceptable match. At this point, the painter needs to rely on his skills to match the vehicle paint by color-matching the paint formulation. Some paint manufacturers provide crude tinting guides, but these guides require the painter to apply complex color science information and relate it to a specific batch of paint using an abstract thought process. These additional steps are time consuming and may still result in a batch of paint having to be discarded or the vehicle having to be repainted.
A software-based system for color-matching relates a particular paint formulation to the VIN or vehicle identification number. While this system may minimizes some problems associated with manufacturing variability, it does not compensate for the natural aging of the paint on the vehicle or for mixing variation that may occur when the painter prepares only a small quantity of paint. The system does not provide guidance in color-matching a paint formulation once it has been mixed.
A spectrophotometric-based technique employs a software program in conjunction with a spcctrophotometer. While such process will approximately match the hue of a painted substrate, they have difficulty accommodating the metallic or pearlescent appearance of some automotive paints. Goniophotometers or multi-angle spectrophotometers improve color-matching results but are sophisticated and expensive pieces of equipment not ideally suited for collision repair facilities.
An additional aspect of color-matching is simulating the clearcoat that is very often applied over the base or color coat on modem vehicle paints. One method involves spraying the paint formulation onto one surface of a high gloss polyester film. The paint is then viewed through the polyester film with the film acting to simulate a clear coating. Although this method is effective for clearcoat simulation, it does not offer the painter guidance on adjusting the color of the paint in order to more accurately match the color of the target substrate.
In view of the foregoing, a need exists for an inexpensive, easy-to-use article to guide the painter in color-matching of a paint formulation to a target substrate, for example, a vehicle under repair.
The present invention provides a method of color-matching a paint formulation to a target substrate using a color-matching article. The methods of color matching according to the present invention guide the painter in selecting the appropriate mixing base(s) for modifying the color of a paint formulation so that it matches the color of the target substrate.
In one embodiment, the method comprises the steps of:
(a) providing a color-matching article comprising:
a transparent base film having a first major surface and a second major surface; and
a colored layer adhered to at least one major surface of the base film, the colored layer including a plurality of transparent colored regions; and
(b) applying the paint formulation over at least a portion of the colored layer to form a paint layer on the color-matching article;
(c) comparing the color-matching article to the target substrate by viewing the paint layer through the transparent base film and colored regions; and
(d) selecting the colored region that most closely matches the color of the target substrate.
In another embodiment, the method comprises the steps of:
(a) providing a color-matching article comprising:
a transparent base film having a first major surface and a second major surface; and a colored layer applied to at least one major surface of the base film, the colored layer including a plurality of colored regions; and
(b) providing a spray-out card having a paintable surface;
(c) applying the paint formulation over the paintable surface of the spray-out card to form a paint layer;
(d) adhering the color-matching article to the paint layer on the spray-out card with an adhesive;
(e) comparing the color-matching article formed in step (d) to the target substrate by viewing the paint layer through the transparent base film and colored regions; and
(f) selecting the colored region that most closely matches the color of the target substrate.
The color-matching article further may optionally include an index that associates at least one transparent colored region with at least one mixing base color. When provided with an index, the method may further include the step of: (e) selecting the mixing base color associated with the colored region selected in step (d) with reference to the index.
Step (d) of the method may comprise the steps of:
(d1) providing an adhesive transfer tape having a first and second major surface;
(d2) adhering one major surface of the adhesive transfer tape to the paint layer on the spray-out card; and
(d3) adhering one major surface of the adhesive transfer tape to the colored layer of the color-matching article.
Step (d) may be conducted, for example, using a portable lamination device.
Color-matching articles useful in the above-described methods of color-matching comprise a color-matching film comprising a base film (having a first major surface and a second major surface) and a colored layer applied to one major surface of the base film. The colored layer includes a plurality of transparent colored regions, for example, 2 to 100 colored regions or, more typically, 10 to 30 colored regions. The color-matching article may also include at least one transparent uncolored region for directly viewing the color of the paint formulation applied to the color-matching article. The transparent colored regions are selected to provide guidance to the painter in color matching. In at least one embodiment, the colored regions are each, preferably, of a different color. Using Commission Internationale de l""Eclairage (CIE) 1976 (L* a* b*) color scale, the colored regions may have a xcex94Eab* value of about 0.2 or greater relative to one another.
In some embodiments, the colored layer is adhered to the second major surface of the base film and the color-matching article further includes an adhesive layer applied over the colored layer. The adhesive layer is useful for bonding the color-matching article to a spray-out card, which provides a substrate for application of the paint formulation to be color-matched. The adhesive layer is preferably a pressure sensitive adhesive which may be directly coated onto the color-matching article, or the adhesive may be provided in the form of an adhesive transfer tape for application to the color-matching article by the painter.
In some embodiments, the color-matching article includes a low-adhesion backsize layer adhered to the transparent base film opposite the adhesive layer. The color-matching article including a pressure sensitive adhesive and a low-adhesion backsize may be conveniently supplied in the form of a roll.
In some embodiments, the color-matching article includes a protective overlay sheet that is releasably attached to the transparent base film. The protective overlay sheet protects the transparent base film from paint overspray (e.g., during application of paint to the color-matching article), scratching and/or other damage that may occur to the transparent base film. The protective overlay sheet is removed prior to comparing the color-matching article to the target substrate. Color-matching articles may include an index that associates at least one of the transparent colored regions with at least one mixing base color. As used herein the term xe2x80x9cmixing basexe2x80x9d or xe2x80x9cmixing base colorxe2x80x9d refers to a standard paint formulation provided by a manufacturer of a brand of paint for use in mixing and color matching of paint formulations. The mixing bases are combined at specific ratios to duplicate the color of the paint. For example, PPG Industries (Strongville, Ohio) manufactures automobile paints under the trade designation xe2x80x9cDELTRON 2000xe2x80x9d. This brand of automobile paints includes a variety of mixing bases identified as xe2x80x9cDMD XXXxe2x80x9d or DMDXXX, where XX or XXX represents a two or three digit numeric code, respectively, identifying the specific mixing base. Examples of other automobile paint manufacturers include BASF, Kansai, Nippon, and DuPont.
In one embodiment, the index comprises a listing of at least one mixing base color printed inside or proximate at least one of the transparent colored regions. In another embodiment, the index comprises a unique symbol identifying each of the plurality of colored regions (e.g., printed inside or proximate each of the colored regions) and a document listing at least one mixing base color for each symbol. In yet another embodiment, the index comprises a document comprising a pictorial representation of the arrangement of the colored regions on the color-matching film and a listing of at least one mixing base code corresponding to each colored region.
Color-matching articles useful in the methods of the present invention may be conveniently supplied in the form of a kit comprising:
(i) a color-matching article comprising:
(a) a color-matching film comprising:
a transparent base film having a first major surface and a second major surface; and p3 a colored layer adhered to at least one major surface of the base film, the colored layer including a plurality of transparent colored regions; and
(b) an index that associates at least one of the colored regions with at least one mixing base color;
(ii) a layer of pressure sensitive adhesive; and
(iii) a spray-out card.
Optionally, the kit for color-matching may further include a laminator for laminating the color-matching article to the spray-out card.